Frequently, the valve springs are tested by removing them from their engine assemblies, and placing them on a laboratory testing device, for example, see U.S. Pat. No. 2,340,277 issued Jan. 25, 1944 to P. A. Sturtevant. Naturally this is an inefficient and time consuming procedure.
Other more recent prior art devices, such as are described in U.S. Pat. Nos.: 3,640,129 issued Feb. 8, 1972 to John C. Bandimere; and 4,186,594 issued Feb. 5, 1980 to William E. Mitchell, an arm or leg member engages the top of a rocker arm, while a pair of tangs grip or surround the push rod.
The obvious disadvantages of these prior art devices are: (1) damage may be caused to a push rod and/or, (2) the rocker arm is rotated in order to depress the valve spring which may cause inaccuracy of the measured spring tension and/or, (3) the devices require a relative large amount of physical effort/strength to operate and/or, (4) are limited in function to being only a valve tester device or a valve lifter device but not both and/or, (5) have limited utility only on a particular type engine for which the device was designed for and/or, (6) require difficult and time consuming setup-mounting on the motor being worked on.
Other prior art patents of interest include U.S. Pat. Nos.: 2,518,408 issued Aug. 8, 1950 to N. B. Weyand; 2,447,109 issued Aug. 17, 1948 to H. R. Billeter; 2,940,166 issued June 14, 1960 to L. E. Moore; 2,527,555 issued Oct. 31, 1950 to J. W. King et al.
These patents are mentioned as being representative of the prior art and other pertinent references may exist. None of the above cited patents are deemed to affect the patentability of the present claimed invention.
The present invention involves a novel combination of features combined in such a way as to afford a solution to the difficulties and disadvantages of the prior art devices.
For example, in contrast to the prior art, the present invention provides a multi-purpose tool for both testing engine mounted valve springs and to facilitate valve spring removal/replacement, while substantially reducing the physical effort/strength required to do each of these tasks. In addition, the present invention enables work to be performed directly on a plurality of different types of engines, for example, diesel, overhead valve motors with push rods or over head cams, rocker arm motors, shaft mounted rocker arm motors and some aircraft engines. The present invention provides a device having a robust and relatively inexpensive structure which combines the capabilities and advantages of both a spring tension tester and a device to facilitate removal of valve springs, enables manipulation and varied arrangement of its constituent parts, is adapted for ease of use, and involves a minimum of associated parts.